tick whose adults feed in the winter and early spring. Pomerant zev (1950) considers "H. scupense" to be a "biological race" of H. detritum.

Life Cycle of H. detritum

The life cycle of H. detritum (= H. mauritanicum) in Algeria has been studied by Sergent, Donatien, Parrot, and Lestoquard (1931B and subsequent works). Larvae hatch in the late autumn

and feed and molt to nymphs on the same host, remaining attached for approximately sixteen days. Nymphs hibernate for approximate_ ly eight months either in groups in cracks and crevices of farm yard walls about six feet above the ground, or under boulders. They are never found in fields without trees and boulders. Hibernation sites are generally those with a warm, sunny exposure, and those nymphs in the warmest places molt earliest in the year (June). Some days after molting, young adults start out in search of a host; they leave their hibernation place at night and travel towards stables, sometimes covering as much as thirty yards a week to reach cattle or horses.

Adults commence attaching to the host in mid June. They mate and feed there, females dropping off after ten to twelve days. Feeding females are most common in July and August; afterwards fewer are found on animals. Those that feed later do not oviposit the same season. Eggs are laid on the ground near animals and hatch in about six weeks. Females die after laying eggs. There appears to be quite a little variation from this typical life cycle.

Males remain on the host for a much longer time than fe males and may move from one host to the other. Nymphs some times move from one host to another.

Note that according to the Algerian reports mentioned above, nymphs hibernate in cracks or crevices of farmyard walls but that almost all Soviet workers, mentioned below, find nymphs alone or with larvae on cattle during the winter. This raises the question whether the Russian and Algerian ticks are actually the same spe cies, and, if so, whether climatic or other factors modify their choice of niches for hibernating in these far-flung areas.

Galuzo (1943) made a special point of the fact that H. detritum is not found in cracks in the walls in southern Kazakstan. As stated four paragraphs below, under certain local conditions in Russia, nymphs may also overwinter off the host. No explanation for these differences in overwintering habits has been found in the Soviet literature.

In southern Kazakstan, Galuzo (1941,1944) reported H. detritum as a two-host tick with unfed nymphs hibernating on cattle during the winter. They engorge and drop from the host in the spring (end of February through April) and molt to adults anywhere from May to August, but mostly in June. Adults disappear in September. Eggs are laid in shaded places in moist meadows, waterside vegetation, or under grass. Larvae aestivate in cracks in the soil or on the surface of the ground until October. Then they ascend grass, attach to grazing cattle, feed, and molt to nymphs on the host. Few nymphs feed and drop from the host before winter.

In Tadzikistan, where H. detritum is most common in irrigated valleys, it has one generation a year (as apparently everywhere else where it occurs), and the seasonal distribution of feeding of the immature and adult stages is like that in Khazakstan (Pavlovsky, Galuzo, and Lototsky 1941).

According to Pomerantzev (1950), when H. detritum is reared in the laboratory nymphs drop from the host any time between October and April. Yet they all undergo the typical winter diapause and molt to adults from May to July, mostly in June. Thus, nymphs that begin life as larvae in October require eight and a half months to become adults, but those that commence feeding as larvae (under experimental conditions) in April require only two months to reach the adult stage. Furthermore, females may fast for six or seven months and feed, between May and August, for from seven to 27 days, average eleven days. After dropping from the host, females commence oviposition in six to 31 days. Eggs number from 5000 to 7000. Larvae appear 25 to sixty days after the eggs have been laid, and may fast for seven or eight months. They (normally) attach to the host about a week after hatching, feed for eleven days, and molt on the host about eleven days later. There is one generation a year.

Pomerantzev (1950) notes that in Middle Asia, (overwintering) nymphs may be found under cattle dung (stored for fuel), and also in the walls of stables (Pavlovsky). Metamorphosis from nymph to adult may occur in buildings and stables thus increasing the importance of the species in the spread of disease.

Life Cycle of "H. scupense"

Knuth, Behn, and Schulze (1918, p. 254) first noted, in their studies of tick-borne diseases in Greece, that "H. scupense" is a single host tick.

According to Pomerantzev (1950), "H. scupense" (which occurs in the Kursk and Saratov areas, lower Volga, Ukrainia, Crimea, Caucasus, Kazakh, Tadzhik, and Yugoslavia, Central Asia, and the rayon of Kogen) is a single-host tick. Adults appear in the winter from January to April and rarely until June. Larvae feed in November, nymphs from November to March.

In the laboratory (Markov, Abramov, and Dzasokhov 1940, as H. volgense), females begin to oviposit from 45 to 85 days after Teaving the host and continue to lay eggs for thirty days. Larvae hatch from 45 to ninety days after commencing oviposition and en gorge in six or seven days. They molt to nymphs on the host, com mence feeding after several days, and feed for four to six days. Nymphs molt to adults, on the same host, ten days afterwards.

In nature, unfed larvae begin to attack cattle in October and molt to the nymphal stage during the same month. The maximum number of nymphs are found in December, when young adults begin to appear. Adults move to different parts of the host and pass the winter on the host. Adults commence feeding early in March. Early in April large numbers of adults leave the hosts. Oviposi tion and development of the eggs occurs during the summer.

Note the long summer period of oviposition and embryological development, whereas the larval and nymphal development is rapid.7 Unfed adults and fed nymphs may undergo a winter diapause. Some engorged nymphs that do not molt remain attached to the host until February. From December to March, adults wander over the host's body but do not start feeding till early spring. The cycle re quires one year.

In northern Caucasus, larval "H. scupense" infest cattle in October and overwinter on the animals. Adults appear early in spring (Markov, Gildenblat, Kurchatov, and Petunin 1948). These workers confirm the single_host life cycle of this tick as does Alfeev (1951) and Melnikova (1953), in his study of the ticks of the Crimean National Forest. There, adults are found on cattle and wild ungulates from September through April but rare individuals may be collected on deer during the summer (May to June). All stages occur on deer during the winter (NovemberDecember) but in January and February only nymphs and adults are found, and by the second half of March all nymphs have molted to adults. In April and the first half of May, only males and greatly engorged females are found on wild ungulates.

Ecology of H. detritum*

In eastern Transcaucasia, H. detritum inhabits various types of desert and steppe areas, described by Pomerantzev, Matikashvily, and Lototsky (1940) (see six paragraphs below). In the Arax val ley of Armenia, Pomerantzev (1934) found this tick only in saline, marshy types of grassland pasture areas, not in Artemesia semi desert areas.

It appears that H. detritum infests a selected variety of semi desert areas, and also steppe and other grassy areas, but not forest zones. It still requires to be explained why H. detritum, which seems to be ecologically more limited than "H. scupense", should have a so much more extensive geographical range than "H. scupense".

Larvae, since they attach to cattle in the cool months of October and November in Tadzhistan and eastern Uzbekistan, select those parts of the host body most exposed to the sun. Summer-feeding adults attach on the shaded undersides of the host (Galuzo 1943).

Among the enemies of these ticks are wagtails (Motacilla spp.), one of which may eat as many as a dozen engorged female ticks from a cow. This bird, and the heron, are considered of importance in the control of H. detritum in Spain (Miranda_ Entrenas 1954).

*See also life cycle of this form above, and ecology of "H. scupense" below.

Ecology of "H. scupense"

The single host type of life cycle, the rapid immature stage feeding period, the long lag between female feeding and oviposition, and the long period of egg laying of this form have already been commented upon, in addition to the phenomenon of adult feeding during the late winter and early spring months.

Pomerantzev (1950) considers that the change in life cycle from a two-host to a single-host type has allowed "H. scupense" to spread further afield geographically than H. detritum. It is assumed that the remark refers to encroachment into otherwise inclement areas, for, so far as now known, the overall geograph ical range of H. detritum is much more extensive than that of "H. scupense".

In their work on the ixodids of Transcaucasia, Pomerantzev, Matikashvily, and Lototsky (1940) list both H. detritum and "H. scupense" as widely spread species in the southern part of the Palearctic Region. Only H. detritum is listed as a "spe cies typical for the desert and steppe formations of eastern Transcaucasia (including salsola, and wormwood salsola forma tions, gramineous wormwood semideserts, Andropogonetum semisteppes and the formations of highland xerophytes of southern Transcaucasia)". "H. scupense" is included under "species equally occurring both in the forest zone of highlands and in desert and steppe formations". Several biological studies on this tick mentioned by Pomerantzev (1950) are unavailable to the writer.7

Melnikova's (1953) study of ticks of the Crimean National Forest showed "H. scupense" to be most common in populated areas adjoining the forest. It is closely associated with the grazing grounds of domestic cattle and wild deer and occurs at all altitudes except that it is much less common in mountain meadows near the peaks (1200 to 1400 meters elevation) and in coniferous forest (500 to 900 meters elevation). It is common in valleys with deciduous and mixed forest (400 to 600 meters), oak forest with many open meadows (600 to 800 meters), and beech forest with small, open fields.